Time-dependent changes in flap-site pain compared with overall surgical pain after oral cancer resection and reconstruction: a retrospective study.

[BACKGROUND] Postoperative analgesia after oral cancer surgery with free-flap reconstruction is complex because pain arises at both donor and recipient sites and likely varies by flap type. Evidence of flap-specific, time-resolved pain and related patient-controlled analgesia (PCA) behaviors is limited.

[METHODS] This single-center retrospective cohort included 127 adults who underwent no flap (n = 53), latissimus dorsi(LD; n = 12), fibula (n = 18), forearm (n = 30), or other flaps (n = 14). Visual analog scale (VAS) scores were recorded for overall pain (0-72 h), recipient-site pain (0-72 h), and donor-site pain (12-72 h). Intravenous PCA consisted of fentanyl (700 or 1400 mcg) plus ketorolac (150 mg). PCA logs provided demand counts, effective deliveries, and infused volumes. Group comparisons were performed using repeated-measures analyses with post hoc tests.

[RESULTS] Baseline characteristics did not differ between groups. Overall VAS scores differed at most time points from 0 to 72 h (all P ≤ 0.013); the fibula group started higher and declined thereafter. Recipient-site pain showed no between-group difference at 60 h but diverged at 72 h (P = 0.026). Donor site pain showed no overall difference, although the fibula tended to remain higher at 12-24 h. In the LD subgroup, recipient-site VAS scores increased again after 48 h. Total anesthesia time differed markedly and was longest in LD cases (P < 0.001). Among flap patients, fentanyl concentration (700 vs. 1400 mcg) did not differ by flap type. Seventy-two-hour cumulative PCA metrics did not differ between groups; however, effective deliveries were higher during the early 12-24 h window (12 h, P = 0.043; 24 h, P = 0.010). At 12 h, endotracheal tube discomfort exceeded recipient- and donor-site pain (Friedman χ = 42.71, P < 0.001).

[CONCLUSION] Flap-specific, time-dependent pain trajectories were identified-early higher pain in fibula and later recipient- or donor-persistence in LD flaps. Early differences in PCA deliveries were not reflected in 72-h totals, indicating a partial dissociation between VAS intensity and analgesic-seeking behavior. These findings support flap-tailored multimodal analgesia and time-resolved PCA adjustments, with attention to airway-related discomfort early after surgery.